A new appeal against the deportation of a family of five asylum seekers from Malawi was last night rejected by the immigration minister, Tony McNulty.

Verah Kachepa and her four children, Natasha, 21, Alex, 17, Tony, 16, and Upile, 11, now face being escorted by immigration officers to Heathrow tomorrow despite a passionate campaign by local people to let them stay in their adopted home of Weymouth, Dorset.

But their supporters will today attempt one final move to keep them in Britain by seeking a judicial review of the case at the high court. If a case can be mounted in time, the family's deportation could be postponed for a second time until new evidence is heard in court.

Mrs Kachepa broke down in tears at her rented flat in Weymouth when local MP Jim Knight relayed the bad news.

"Why me? What have I done to deserve this?" she said, as her children joined her after a day spent paying what they feared would be final visits to their friends in the area.

Louise Christian, the human rights lawyer who assembled a new 50-page dossier of evidence submitted to Mr McNulty, criticised the government's decision not to grant compassionate leave to remain. She also warned the family's supporters it would be difficult to assemble a case for a judicial review before their scheduled deportation.

"It's a decision completely lacking in compassion," she said. "The Kachepas are clearly the sort of people who we need in our country. Natasha was training to be a nurse and to treat children in this way is appalling and traumatising.

"This isn't just about the family, this is about the whole community of Weymouth. The minister should have regard to the very strong, almost unanimous, feelings in the area."

Mr McNulty rejected new evidence from expert witnesses of the dangers they face in Malawi and testimony of their psychological suffering from the Helen Bamber Foundation, on a day when the government came under pressure for its failure to deport asylum seekers. Former home secretary Ann Widdecombe, who has supported the Kachepas, has described them as "soft targets" for an administration desperate to show it has control over asylum and immigration.

Ralph Johnson, who has led the campaign to keep the family in Dorset, said Mrs Kachepa had continued to help other people in the local area despite her suffering. "It is a cruel and inhumane decision. I cannot believe that Mr McNulty has ignored the new evidence."

Last month the family packed their belongings and travelled to Heathrow in readiness to be deported only to find immigration officers had mislaid their paperwork and were unable to deport them. The Home Office subsequently apologised for the additional stress of what Mr Knight described as a "fiasco".

It followed a successful campaign by local people to free the family from a sudden incarceration in Yarls Wood detention centre, near Bedford, after nearly five years as residents in Weymouth. But a protest at Westminster, personal appeals by Mr Knight and cross-party support from Ms Widdecombe and George Galloway have fallen on deaf ears.

Banned from paid employment because she is an asylum seeker, Mrs Kachepa has volunteered for local charities, including as a prison visitor and for a care service for pregnant women. Natasha has just got engaged to Tom Sanderson, a soldier who was injured on duty in Iraq.

The family arrived in Britain legally in 2001 to join her husband, who was working as a pharmacist but he abandoned them, leaving behind large debts, which Mrs Kachepa paid off with two jobs. When Mrs Kachepa was warned never to return to Malawi after her ex-husband moved in with a niece of the former dictator Hastings Banda she claimed asylum, fearing for her safety if forcibly returned to her homeland.

A report by the Medical Foundation for the Victims of Torture detailed the domestic violence Mrs Kachepa suffered during her marriage and found the continued uncertainty over their status had caused considerable psychological damage to the family.